Btukfyl

I have text where I want to adjust the space above the first line. I want to overlay grid lines to show where the vertical position of the text is.

The MWE below with the following line commented is the standard output. The red horizontal lines are integer multiples of baselineskip from the top.

%defIncludeDesiredTopSkip{}

However, if I uncomment this line (which applies the DesiredTopSkip, which is set to 0pt here), I obtain the following:

defIncludeDesiredTopSkip{}

Note that the baseline now is exactly on the line.

Question:

What am I missing that would explain this discrepancy in the two cases and how do I get both cases to properly display the baseline?

Note:

• In case anyone is curious as to why I want to do this: These lines are then used to compute the parshape parameters based on where these lines intersect the particular shape.

References:

• Why does vspace*{0pt} add vertical space?.




• Confused with TeX terminology: height, depth, width

Code:

%defIncludeDesiredTopSkip{}

documentclass{article}

usepackage{showframe}

usepackage{tikz}



usepackage[paperwidth=7.0cm]{geometry}



newcommand*{DesiredTopSkip}{0pt}



newcommand*{ShowTextGuideLines}[1]{%

begin{tikzpicture}[remember picture, overlay]

    coordinate (X) at ([

            xshift=1.0in+hoffset+oddsidemargin,

            yshift=-1.0in-voffset-topmargin-headheight-headsep%

        ]current page.north west);



    node [draw=red, fill=yellow] at (X) {X};%% DEBUGGING: Ensure (X) is the correct spot.



    foreach X in {1, ..., #1} {%

        draw [thin, red] ([yshift=-Xbaselineskip-DesiredTopSkip]X) -- ++ (hsize,0);

    }%

end{tikzpicture}%

}%



begin{document}

ifdefinedIncludeDesiredTopSkip

    %% See comments in https://tex.stackexchange.com/q/7676/4301

    hbox{}kern-topskip%

    vspace*{DesiredTopSkip}%

fi

First line. abcdefghij

par

Second line. abcdefghij

ShowTextGuideLines{3}

end{document}